Definition and general context

Three-phase transformers are essential electrical devices for the efficient transmission and distribution of electrical energy in three-phase alternating current systems. Its main function is to transform voltage and current levels between different circuits, maintaining constant active power, which facilitates the adaptation of energy for different industrial, commercial and residential uses.

This type of transformer is made up of three primary and secondary windings, one for each phase, integrated into a single magnetic core or into separate cores, optimizing space and costs compared to the use of three independent single-phase transformers. Its design and configuration allow balanced and safe operation in three-phase systems, which are the basis of most modern electrical networks.

Electromagnetic fundamentals

The basic principle that governs the operation of three-phase transformers is Faraday's law of electromagnetic induction, which states that an induced voltage is generated in a conductor when the magnetic flux passing through it varies over time. In a transformer, the primary winding creates an alternating magnetic flux in the core, which induces a voltage in the secondary winding.

In three-phase transformers, this process occurs simultaneously for all three phases, whose windings are spatially positioned at 120 electrical degrees to each other. This allows the generation of magnetic fluxes displaced in time, guaranteeing a constant and balanced energy transfer between the phases.

The transformer core is designed to concentrate and channel the magnetic flux, minimizing dispersion losses and optimizing energy efficiency. Furthermore, the turns ratio between windings defines the voltage transformation, adjusting the electrical levels according to the needs of the system.

Transformation ratio and phase balance

The transformation ratio in a three-phase transformer is the proportion between the number of turns of the primary and secondary windings, which determines the voltage change. This relationship is crucial for adapting electrical characteristics between different sections of the network, such as raising voltage for transmission or reducing it for distribution.